NaSn5: An Intermetallic Compound with Covalent α-Tin and Metallic β-Tin Structure Motifs

A novel and unusual three-dimensional network of tin atoms is present in NaSn₅, in which metallic layers analogous to those in β-Sn alternate with tetravalent units analogous to α-Sn. The compound shows the emergence of pentagonal-dodecahedral units from the metallic β-Sn modification (see structure on the right; all unlabeled spheres are Sn atoms). Quantum-mechanical investigations indicate the simultaneous presence of structural regions with localized and delocalized bonds.     

Ca3Au6.61Ga4.39 – A New Gallide with a Three‐Dimensional Gold–Gallium Network

Ca₃Au_6.61Ga_4.39 was synthesized by reacting the elements in a glassy carbon crucible under argon in a water‐cooled sample chamber in a high‐frequency furnace. The compound crystallizes with a new hexagonal structure type, space group P6₃/mmc: Z = 2, a = 926.6(2), c = 733.1(2) pm, wR2 = 0.0832, 328 F values and 20 variables. This structure type consists of a remarkably complex three‐dimensional [Au_6.61Ga_4.39] network with significant Au–Au, Au–Ga, and Ga–Ga interactions. The calcium atoms are located within slightly distorted hexagonal channels of the gold–gallium network. The structural relations to the AlB₂ and Er₂RhSi₃ type structures are discussed.     

K13CoSn17–x (x = 0.1): A New Ternary Phase Containing ­Cobalt Centered [Sn9] Cluster Synthesized via High‐Temperature Reaction

A new ternary potassium cobalt stannide, K₁₃CoSn_17–x (x = 0.1), was obtained by reacting the mixture of the corresponding pure elements at high temperature, and structurally characterized by single‐crystal X‐ray diffraction study. K₁₃CoSn_17–x (x = 0.1) crystallizes in the orthorhombic space group Pbca (No. 61) with a = 26.2799(7) Å, b = 24.1541(6) Å, c = 29.8839(6) Å, V = 18969.3(8) ų, and Z = 16. Its structure contains isolated [CoSn₉] monocapped square antiprism and [Sn₄] tetrahedron in the ratio 1:2, forming a hierarchical variant of Laves phase MgZn₂. The structural relation between the title compound with MgZn₂ as well as other binary stannides is also discussed.     

A New Compound in the Cu‐In System – the Synthesis and Structure of Cu10In7

A new binary phase, Cu₁₀In₇, was found during the investigation of the η‐phase field in the Cu‐In system. Single crystals of Cu₁₀In₇ were grown from a melt under an inert atmosphere. The compound crystallizes in the monoclinic space group C2/m with cell parameters a = 13.8453(2) Å, b = 11.8462(1) Å, c = 6.7388(1) Å and β = 91.063(1). The structure is based on a unit of face‐sharing octahedra consisting of five Cu₄In₂ octahedra terminated by Cu₅In octahedra at both ends. The crystal structure is closely related to the Cu₁₁In₉ structure type.     

[(PhSnS3)2(CuPPhMe2)6], ein sechskerniger Kupfer(I)‐Komplex mit PhSnS3‐Liganden

[(PhSnS₃)₂(CuPPhMe₂)₆], a Hexanuclear Copper(I) Complex with PhSnS₃ Ligands Na₃[PhSnS₃] which is available by the cleavage of Ph₄Sn₄S₆ with Na₂S in aqueous THF reacts with the copper(I) complex [(PhPMe₂)bipyCuCl] to give the hexanuclear copper(I) compound [(PhSnS₃)₂(CuPPhMe₂)₆] ( 1 ). 1 crystallizes in the space group P2₁/n with a = 1343.4(3) pm, b = 1134.5(2) pm, c = 2353.0(7) pm, β = 98.04(3)° (at 220 K). The molecular structure of 1 consists of six Cu(PPhMe₂) groups which are bridged by two PhSnS₃ units. The copper atoms are coordinated by two sulfur atoms and a terminal phosphine ligand in nearly planar arrangement with Cu‐S distances ranging between 223.6(2) and 232.9(2) pm.     

Zur Abgrenzung der PbFCl‐ und Cu2Sb‐Strukturfamilien: Neubestimmung und Verfeinerung der Kristallstrukturen von CuMgSb,Cu2Sb und CuMgAs

Demarcation of the PbFCl and Cu₂Sb Structure Families: Crystal Structure Re‐Determinations and Refinements of CuMgSb, Cu₂Sb, and CuMgAs The crystal structures of CuMgSb, Cu₂Sb, and CuMgAs have been re‐determined and refined from single crystal data, and the structural relationship between CuMgSb (cubic), Cu₂Sb (tetragonal) and CuMgAs (orthorhombic) is discussed in detail. CuMgAs does not crystallize in the Cu₂Sb type, as assumed until now; but in a new structure type oP24 (Pnma; Z = 8): a = 1346.0(1) pm, b = 395.40(3) pm, c = 739.58(6) pm. The structure is related to Cu₂Sb and can be derived from it following the principle of ′chemical twinning′. The re‐determined parameters of Cu₂Sb are included in a structure field diagram together with additional representatives of the PbFCl type. The structure field can be devided into three regions with the prototypes PbFCl, Cu₂Sb, and Fe₂As, respectively. The assignment can be related to the predominant type of bonding of each structure.     

Intermetallic Gold Compounds REAuMg (RE = Y,La–Nd,Sm, Eu,Gd–Yb)

New intermetallic rare earth compounds REAuMg (RE = Y, La–Nd, Sm, Eu, Gd–Yb) were synthesized by reaction of the elements in sealed tantalum tubes in a high‐frequency furnace. The compounds were investigated by X‐ray diffraction both on powders and single crystals. Some structures were refined on the basis of single crystal data. The compounds with Y, La–Nd, Sm, and Gd–Tm adopt the ZrNiAl type structure with space group P62m: a = 770.8(2), c = 419.5(1) pm, wR2 = 0.0269, 261 F² values for PrAuMg, a = 750.9(2), c = 407.7(1) pm, wR2 = 0.0561, 649 F² values for HoAuMg with 15 variables for each refinement. Geometrical motifs in HoAuMg are two types of gold centered trigonal prisms: [Au1Mg₃Ho₆] and [Au2Mg₆Ho₃]. The gold and magnesium atoms form a three‐dimensional [AuMg] polyanion in which the holmium atoms fill distorted hexagonal channels. The magnesium positions show a small degree of magnesium/gold mixing resulting in the refined compositions PrAu_1.012(2)Mg_0.988(2) and HoAu_1.026(3)Mg_0.974(3). EuAuMg and YbAuMg contain divalent europium and ytterbium, respectively. Both compounds crystallize with the TiNiSi type structure, space group Pnma: a = 760.6(3), b = 448.8(2), c = 875.8(2) pm, wR2 = 0.0491, 702 F² values, 22 variables for EuAuMg, and a = 738.4(1), b = 436.2(1), c = 864.6(2) pm, wR2 = 0.0442, 451 F² values, and 20 variables for YbAuMg. The europium position shows a small degree of europium/magnesium mixing, and the magnesium site a slight magnesium/gold mixing leading to the refined composition Eu_0.962(3)Au_1.012(3)Mg_1.026(3). No mixed occupancies were found in YbAuMg where all sites are fully occupied. In these structures the europium(ytterbium) and magnesium atoms form zig‐zag chains of egde‐sharing trigonal prisms which are centered by the gold atoms. As is typical for TiNiSi type compounds, also in EuAuMg and YbAuMg a three‐dimensional [AuMg] polyanion occurs in which the europium(ytterbium) atoms are embedded. The degree of distortion of the two polyanions, however, is different.     

Zn‐rich Zincides of the Ternary System Ca–Mg–Zn: Synthesis,Crystal structure,Chemical Bonding

In the course of a study on the role of magnesium in polar zincides of the heavier alkaline‐earth elements, three intermetallic phases of the ternary system Ca–Mg–Zn were synthesized from melts of the elements and their structures were determined by means of single‐crystal X‐ray data. Starting from the binary zincide CaZn₁₁, the phase width of the BaCd₁₁‐type structure reaches up to the fully ordered stoichiometric compound CaMgZn₁₀ [tI48, space group I4₁/amd, a = 1082.66(6), c = 688.95(5) pm, Z = 4, R₁ = 0.0239]. The new compound CaMgZn₅ (oP28, space group Pnma, a = 867.48(3), b = 530.37(5), c = 1104.45(9) pm, Z = 4, R₁ = 0.0385) crystallizes in the CeCu₆‐type structure, exhibits no Mg/Zn phase width and has no binary border equivalent in the system Ca–Mg–Zn. Similar to the situation in CaMgZn₁₀, one M position of the aristotype has a slightly larger coordination sphere (CN = 14) and is accordingly occupied by the larger Mg atoms. The third phase, Ca_2+xMg_6–x–yZn_15+y (hP92, space group P6₃/mmc, a = 1476.00(5), c = 881.01(4) pm, Z = 4, R₁ = 0.0399 for Ca_2.67Mg_5.18Zn_15.15) forms the hexagonal Sm₃Mg₁₃Zn₃₀‐type structure also known as μ‐MgZnRE or S phase. A small phase width (x = 0–0.67; y = 0–0.58) is due to the slightly variable Ca or Zn content of the two Mg positions. The structure is described as an intergrowth of the hexagonal MgZn₂ Laves phase and the CaZn₂ structure (KHg₂‐type). All compounds exhibit strong Zn–Zn and polar Mg–Zn covalent bonds, which are visible in the calculated electron density maps. Their structures are thus herein described using the full space tilings of [Zn₄] and [MgZn₃] tetrahedra, which are fused to polyanions consisting of tetrahedra stars, icosahedra segments etc. and the large (CN = 18–22) Ca cation coordination polyhedra. Pseudo bandgaps apparent in the tDOS are compatible with the narrow v.e./M ranges observed for other isotypic members of the three structure types.     

Pniktogenidostannate(IV) mit isolierten Tetraeder‐Anionen: Neue Vertreter (E1)4(E2)2[Sn(E15)4] (mit E1 = Na,K; E2 = Ca,Sr, Ba; E15 = P,As, Sb,Bi) vom Na6[ZnO4]‐Typ und die Überstrukturvariante von K4Sr2[SnAs4]

Pnictogenidostannates(IV) with Discrete Tetrahedral Anions: New Representatives (E1)₄(E2)₂[Sn(E15)₄] (with E1 = Na, K; E2 = Ca, Sr, Ba; E15 = P, As, Sb, Bi) of the Na₆[ZnO₄] Type and the Superstructure Variant of K₄Sr₂[SnAs₄] The silvery to dark metallic lustrous compounds (E1)₄(E2)₂[Sn(E15)₄] (E1 = Na, K; E2 = Ca, Sr, Ba; E15 = P, As, Sb, Bi) were prepared from melts of stoichiometric mixtures of the elements. They crystallize in the Na₆[ZnO₄]‐type structure (hexagonal, space group: P6₃mc, Z = 2; Na₄Ca₂[SnP₄]: a = 938.94(7), c = 710.09(8) pm; K₄Sr₂[SnAs₄]: a = 1045.0(2), c = 767.0(1) pm; K₄Ba₂[SnP₄]: a = 1029.1(6), c = 780.2(4) pm; K₄Ba₂[SnAs₄]: a = 1051.3(1), c = 795.79(7) pm; K₄Ba₂[SnSb₄]: a = 1116.9(2), c = 829.2(1) pm; K₄Ba₂[SnBi₄]: a = 1139.5(2), c = 832.0(2) pm). The anionic partial structure consists of tetrahedra [Sn(E15)₄]^8– orientated all in the same direction along [001]. In the cationic partial structure one of the two cation positions is occupied statistically by alkali and alkaline earth metal atoms. Up to now only for K₄Sr₂[SnAs₄] a second modification could be isolated, forming a superstructure type with three times the unit cell volume (hexagonal, space group: P6₃cm, Z = 6; a = 1801.3(2), c = 767.00(9) pm) and an ordered cationic partial structure.     

Substitution Effects in Zintl Phases: Synthesis and Crystal Structure of the Novel Phases Ae3Sn4−xBi1+x (x ≤ 1; Ae = Sr,Ba) Containing Shubnikov‐Type Nets $^{2}_{\infty}\rm [Sn_{4-x}Bi_{x}]$

The compounds Ae₃Sn_4?xBi_1+x (Ae = Sr, Ba) with x < 1 have been synthesized by solid‐state reactions in welded Nb tubes at high temperature. Their structures were determined by single crystal X‐ray diffraction studies to be tetragonal; space group I4/mcm (No. 140); Z = 4, with a = 8.968(1) Å, c = 12.859(1) Å for Sr₃Sn_3.36Bi_1.64(3) ( 1 ) and a = 9.248(2), c = 13.323(3) Å for Ba₃Sn_3.16Bi_1.84(3) ( 2 ). The structure consists of two interpenetrating networks formed by a 3D Ae_6/2Bi substructure (anti‐ReO₃ type) forming the host, and layers of interconnected four‐member units [Sn_4?xBi_x] with “butterfly”‐like shape as the guest. According to the Zintl‐Klemm concept, the compounds are slightly electron deficient and will be charge balanced for x = 1. The electronic structures of Ae₃Sn_4?xBi_1+x calculated by the TB‐LMTO‐ASA method indicate that the compounds correspond to ideal semiconducting Zintl phases with a narrow band gap for x = 1 (zero‐gap semiconductor). The origin of the slight deviation from the optimal electron count for a valance compound is discussed.     

Synthese und Kristallstruktur des gemischt‐valenten Komplexes [Sn2I3(NPPh3)3]

Synthesis and Crystal Structure of the Mixed Valent Complex [Sn₂I₃(NPPh₃)₃] The mixed valent phosphoraneiminato complex [Sn₂I₃(NPPh₃)₃] ( 1 ) was prepared by the reaction of the tin(II) complex [SnI(NPPh₃)]₂ with sodium in tetrahydrofuran. 1 crystallizes with two formula units of THF to form yellow, moisture sensitive single crystals, which were characterized by a crystal structure determination. 1 · 2 THF: Space group P2₁/c, Z = 4, lattice dimensions at –80 °C: a = 1964.5(2), b = 1766.0(2), c = 2058.6(2) pm; β = 118.33(1)°, R = 0.052. 1 forms dimeric molecules in which the tin atoms are linked by two nitrogen atoms of two (NPPh₃^–) groups to form a planar Sn₂N₂ four‐membered ring. The Sn^IV atom is additionally coordinated by a terminal iodine atom and by a terminal (NPPh₃^–) group, whereas the Sn^II atom is additionally coordinated by two iodine atoms forming a ψ trigonal‐bipyramidal surrounding.     

CrB‐Type Phases in the Tb‐Zr‐Al‐Si System

The crystal structures of Tb(Al_0.15Si_0.85), (Tb_0.70Zr_0.30)(Al_0.17Si_0.83) and Zr(Al_0.22Si_0.78) have been refined from single‐crystal X‐ray diffraction data. The three compounds crystallize with CrB‐type structures (Pearson symbol oS8, space group Cmcm): Tb(Al_0.15Si_0.85): a = 4.2715(5), b = 10.5595(15), c = 3.8393(5) Å; (Tb_0.70Zr_0.30)(Al_0.17Si_0.83): a = 4.163(2), b = 10.423(5), c = 3.8543(18) Å; Zr(Al_0.22Si_0.78): a = 3.7824(6), b = 10.0164(16), c = 3.7795(5) Å. The existence of a significant CrB‐type solid solution in the quaternary system Tb‐Zr‐Al‐Si, based on the ternary compound Tb(Al_0.15Si_0.85) and extending toward the solid solution based on the binary compound ZrSi in the Zr‐Al‐Si system, cannot be excluded.     

Phosphorus Oligomerization in Zintl Phases: Synthesis,Crystal Structure,and Bonding Analysis of Mixed Alkali and Alkaline‐Earth Metal Phosphides

Pnictides α‐Ba₅P₄ and KBa₄P₅ were prepared by melting the elements. The α‐Ba₅P₄ compound crystallizes in the orthorhombic system (Sm₅Ge₄‐type), space group Pnma, Z = 4, a = 8.330(3), b = 16.503(3), c = 8.405(2)Å, it contains two anionic species : P₂^4— dumbbells and P^3—. The KBa₄P₅ compound crystallizes in the tetragonal system, space group P4₃2₁2, Z = 4, a = 8.559(1), c = 16.102(2)Å, it contains trimers P₃^5— and dumbbells P₂^4—. The crystal structures were solved from single crystal X‐ray data and refined by full‐matrix least‐squares to agreement factors R1 = 0.047 and 0.038, respectively. Using ionic charges, α‐Ba₅P₄ is formulated as [5Ba²⁺, 2P^3—, P₂^4—] and KBa₄P₅ as [K⁺, 4Ba²⁺, P₂^4—, P₃^5—]. The level of oligomerisation in these structures depends upon the overall valence electron content, bonding within the anionic oligomers has been analyzed on the basis of EHMO calculations and compared to classical or hypervalent bonding in other phosphide compounds.     

Intermetallic Compounds and the Use of Atomic Radii in Their Description

Metallic radii, which are obtained from atomic distances in the pure elements, are generally used for the calculation of distances in intermetallic compounds. However, the procedure for using such radii depends on the individual structural type: (a) For high coordination numbers and only slightly differing distances between atoms of the same kind and different atoms, all distances in a structure are proportional to the sum of radii, weighted according to the compositon. Such a “Vegard” relationship for ordered compounds is obeyed by intermetallic compounds with topological close packings, but strictly only if the various kinds of distances are correlated via symmetry relationships. For compounds with low coordination numbers the simple sum of radii holds for atoms participating in the shortest bond (e.g. in ionic crystals).-(b) The number of neighbors determines the size of each atom. It can be shown that the bond strength-bond length concept, developed for valence compounds, and often dealt with in the literature over the last ten years, is also applicable for alloys. On this basis a formalism is developed which uniformly describes the size of the atoms as a function of the coordination number for both the limiting cases of multiple bonds in molecules and for close packed atomic arrangements in alloys.     

Der Chemische Transport von Kupfer/Gallium‐ und Silber/Gallium‐Phasen

Chemical Vapor Transport of Intermetallic Systems. 10. Chemical Transport of Copper/Gallium and Silver/Gallium Phases The solid solution of gallium in copper and the ζ‐ and the γ‐phase can be prepared by CVT‐methods using iodine as transport agent. The solid solution of gallium in silver and the ζ‐phase and the ζ′‐phase can also prepared by CVT‐methods. Thermodynamic calculations allow to understand why these phases can be prepared by this manner.     

Destruktive Komplexierung des dimeren Diorganylzinn(IV)‐hydroxids [Me2Sn(A)(μ‐OH)]2 (HA = Benzol‐1,2‐disulfonsäureimid): Bildung und Strukturen der Einkernkomplexe [Me2Sn(A)2(OPPh3)2] und [Me2Sn(phen)2]2⊕ · 2 A⊖ · MeCN

Polysulfonylamines. CXVI. Destructive Complexation of the Dimeric Diorganyltin(IV) Hydroxide [Me₂Sn(A)(μ‐OH)]₂ (HA = Benzene‐1,2‐disulfonimide): Formation and Structures of the Mononuclear Complexes [Me₂Sn(A)₂(OPPh₃)₂] and [Me₂Sn(phen)₂]^2⊕ · 2 A^⊖ · MeCN Destructive complexation of the dimeric hydroxide [Me₂Sn(A)(μ‐OH)]₂, where A^⊖ is deprotonated benzene‐1,2‐disulfonimide, with two equivalents of triphenylphosphine oxide or 1,10‐phenanthroline in hot MeCN produced, along with Me₂SnO and water, the novel coordination compounds [Me₂Sn(A)₂(OPPh₃)₂] ( 3 , triclinic, space group P 1) and [Me₂Sn(phen)₂]^2⊕ · 2 A^⊖ · MeCN ( 4 , monoclinic, P2₁/c). In the uncharged all‐trans octahedral complex 3 , the heteroligands are unidentally O‐bonded to the tin atom, which resides on a crystallographic centre of inversion [Sn–O(S) 227.4(2), Sn–O(P) 219.6(2) pm, cis‐angles in the range 87–93°; anionic ligand partially disordered over two equally populated sites for N, two S and non‐coordinating O atoms]. The cation occurring in the crystal of 4 has a severely distorted cis‐octahedral C₂N₄ coordination geometry around tin and represents the first authenticated example of a dicationic tin(IV) dichelate [R₂Sn(L–L′)₂]^2⊕ to adopt a cis‐structure [C–Sn–C 108.44(11)°]. The five‐membered chelate rings are nearly planar, with similar bite angles of the bidentate ligands, but unsymmetric Sn–N bond lengths, each of the longer bonds being trans to a methyl group [ring 1: N–Sn–N 71.24(7)°, Sn–N 226.81(19) and 237.5(2) pm; ring 2: 71.63(7)°, 228.0(2) and 232.20(19) pm]. In both structures, the bicyclic and effectively C_S symmetric A^⊖ ions have their five‐membered rings distorted into an envelope conformation, with N atoms displaced by 28–43 pm from the corresponding C₆S₂ mean plane.     

Tin-magnesium substitution in Ir3Sn7—structure and chemical bonding in MgxIr3Sn7-x (x=0-1.67)

Well-shaped single crystals of binary Ir₃Sn₇ were obtained from a tin flux (starting composition Ir:Sn=1:10). The magnesium based stannides Mg_xIr₃Sn_7-x (x=0.61-1.67) were synthesized from the elements in glassy carbon crucibles in a water-cooled sample chamber of a high-frequency furnace. The samples were characterized by X-ray diffraction on powders and single crystals. All compounds crystallize with the cubic Ir₃Ge₇ type structure (space group Imm, Z=4). In this structure type the p-block atoms occupy the Wyckoff positions 12d and 16f and form two interpenetrating frameworks consisting of cubes and square antiprisms. The transition metal atoms center the square antiprisms and are arranged in pairs. With increasing magnesium substitution the lattice parameter of Ir₃Sn₇ (935.3 pm) decreases from 934.7 pm (x=0.61) to 930.6 pm (x=1.67) and the Ir-Ir distances decrease from 294 pm (Ir₃Sn₇) to 290 pm (Mg_1.67Ir₃Sn_5.33). In the ternary compounds Mg substitutes Sn on both framework sites. However, the 12d site shows a substantially larger preference for Mg occupation. By performing first-principles calculations we investigated the bonding situation in Ir₃Sn₇ and its alteration upon Mg incorporation. For binary Ir₃Sn₇ there are considerable bonding interactions between Ir and Sn atoms (d-p bonding) and between neighboring Sn atoms on the site 16f (p-p bonding). Both types of interactions diminish when substituting Sn for Mg. This explains the different site preference of Mg in Mg_xIr₃Sn_7−x: Mg occupation of the site 12d retains covalent p-p framework bonding between 16f atoms in the ternary compounds.     

Two‐ and Three‐Dimensional [IrSi] Networks in the Silicides Sm3Ir2Si2, HoIrSi,and YbIrSi

New intermetallic rare earth iridium silicides Sm₃Ir₂Si₂, HoIrSi, and YbIrSi were synthesized by reaction of the elements in sealed tantalum tubes in a high‐frequency furnace. The compounds were investigated by X‐ray diffraction both on powders and single crystals. HoIrSi and YbIrSi crystallize in a TiNiSi type structure, space group Pnma: a = 677.1(1), b = 417.37(6), c = 745.1(1) pm, wR2 = 0.0930, 340 F² values for HoIrSi, and a = 667.2(2), b = 414.16(8), c = 742.8(2) pm, wR2 = 0.0370, 262 F² values for YbIrSi with 20 parameters for each refinement. The iridium and silicon atoms build a three‐dimensional [IrSi] network in which the holmium(ytterbium) atoms are located in distorted hexagonal channels. Short Ir–Si distances (246–256 pm in YbIrSi) are indicative for strong Ir–Si bonding. Sm₃Ir₂Si₂ crystallizes in a site occupancy variant of the W₃CoB₃ type: Cmcm, a = 409.69(2), b = 1059.32(7), c = 1327.53(8) pm, wR2 = 0.0995, 383 F² values and 27 variables. The Ir1, Ir2, and Si atoms occupy the Co, B2, and B1 positions of W₃CoB₃, leading to eight‐membered Ir₄Si₄ rings within the puckered two‐dimensional [IrSi] network. The Ir–Si distances range from 245 to 251 pm. The [IrSi] networks are separated by the samarium atoms. Chemical bonding in HoIrSi, YbIrSi, and Sm₃Ir₂Si₂ is briefly discussed.